Study On Preparation Of Metal-carbon Active Electrode By Electrodeposition Method And Its Performance In Water Splitting

In order to meet the needs of the rapid development of human society,fossil energy sources such as oil,natural gas,and coal have been developed and utilized in a transitional manner,which has exacerbated the already serious environmental pollution and energy crisis problems.Therefore,it is particularly important to develop renewable and clean energy technologies that can be used efficiently,as well as new energy storage and conversion technologies.In recent years,the technology for preparing hydrogen by electrolysis of water has been rapidly developed.The main factors restricting the progress of electrolysis of water are the oxygen evolution reaction(OER)that occurs at the anode,and the hydrogen evolution reaction(HER)that occurs at the cathode.In this paper,electrodeposition method was used to compound carbon quantum dots doped with different elements with nickel-iron and ruthenium respectively to prepare active electrodes.Through the addition of nitrogen-doped carbon quantum dots,a nitrogen-doped carbon layer is formed,in which nitrogen atoms are used as coordinating atoms to coordinate with metal atoms to form a metalnitrogen/carbon structure,which is beneficial to the metal clusters The improved electron transport and the exposure of more catalytic sites will ultimately help promote the catalytic performance of metal clusters for oxygen evolution and hydrogen evolution.The effects of electrolyte concentration,electrodeposition time,heat treatment temperature,ratio of metal ions to carbon quantum dots,and carbon quantum dots with different doping elements on the catalytic performance of metal-carbon active electrodes were explored.The main research results of this paper are as follows:1.The precursors of carbon quantum dots doped with nitrogen,boron,and phosphorus for compounding with metals were prepared,and the element composition,functional group types,microstructure and particle size distribution of three different element-doped carbon quantum dots were explored law.2.A metal-carbon active electrode composed of nitrogen-doped carbon quantum dots and nickel-iron composite was prepared,which was used to electrocatalyze the oxygen evolution reaction.The effects of electrodeposition time,carbon quantum dot concentration,metal concentration and other parameters on the catalytic performance of the active electrode were explored respectively.The results show that with the addition of nitrogen-doped carbon quantum dots,a nitrogen-doped carbon layer is formed,which facilitates the charge transfer.Moreover,after the carbon layer is combined with the metal clusters,a rough surface structure is formed,which increases the surface area of the catalytic reaction.The active electrode prepared under the optimal electrodeposition conditions has an overpotential of only 195 mV at a current density of 10 mA cm-2 for the catalytic reaction of oxygen evolution,which is better than the noble metal catalysts used in commercial applications.3.A metal-carbon active electrode composed of nitrogen,phosphorus and boron doped carbon quantum dots and ruthenium is prepared,which is used to electrocatalyze the hydrogen evolution reaction.The effects of electrodeposition time,and other parameters on the catalytic performance of the active electrode were explored respectively.The results show that the carbon layer formed by the addition of nitrogen-doped carbon quantum dots contributes to the transfer of electric charges.In addition,after the addition of boron element,due to its positive charge and the small size of boron atom,it exposes more catalytic sites while increasing the charge transfer,and finally further improving the catalytic activity of hydrogen evolution.However,when phosphorus is doped,due to its negative charge and large phosphorus atom size,it hinders the transfer of charges between metal clusters and reduces the catalytic performance of hydrogen precipitation.The overpotential of the active electrode prepared under the optimal electrodeposition conditions is-69 mV and-172 mV at current densities of-10 mA cm-2 and-100 mA cm-2,which are better than commercial ones.Noble metal catalysts used in.